The invention relates to a method of and a device for the electrographic printing of electrically stored information, using a cathode ray tube whose luminescent layer is line-sequentially scanned by a cathode beam in accordance with the information stored, and also using a photoconductive record carrier on the photoconductive layer of which a mosaic-like latent charge image is formed by the activated luminescent layer of the cathode ray tube via an optical system, said charge image being subsequently developed and the developed image being transferred to a further record carrier, the minimum line frequency with which the cathode beam is deflected corresponding to the quotient of the transport speed of the record carrier and the line interval.
From U.S. Pat. No. 3,947,190 an electrophotographic apparatus is known in which the light-emitting elements of a character to be printed which are activated on the display screen of a cathode ray tube are optically transferred to a record carrier by way of an optical system which consists of mirrors and lenses. The complete character is displayed matrix-wise on the display screen and is transferred to the record carrier. The electron beam of the tube is to be horizontically and vertically deflected for this purpose. In order to keep the dimensions of the tube small, the individual light-emitting elements are smaller than the pixels to be recorded on the record carrier, so that the optical system must perform an enlargement of the light-emitting elements to be transferred. However, the lack of definition of the light-emitting elements is also increased, so that a hazy print of the image to be recorded is obtained on the record carrier. Moreover, the brightness of the light-emitting element to be transferred, thus, also decreases. These drawbacks could be mitigated to some extent by increasing the beam current of the cathode ray tube, but they cannot be avoided in that manner. Furthermore, there is a drawback in that the record carrier must remain stationary during the character transfer from the cathode ray tube. Thus, the transport of the record carrier is intermittent. This implies a comparatively high energy consumption and a complex technical construction which is, moreover, subject to substantial wear.
Furthermore, from U.K. Patent Application No. 2047916A, published Dec. 3, 1980, an electrophotographic printer is known in which the display screen of the cathode ray tube comprises optical fibers which transfer the activated light image directly to the record carrier without a special optical system. However, because the optical fibers cannot be arranged near the record carrier because of contamination of the fibers by the developer and the risk of damaging of the fibers, the light spot to be transferred is again enlarged, so that a low resolution of the latent image on the record carrier is obtained. Moreover, this device has the drawback that, in order to maintain a small, constant distance between the optical fibers and the record carrier, a precision positioning and adjustment mechanism is required.